Renewable electrical fuse



Sept. 28, 1943. H, w. MERv|s` RENEWABLE ELECTRICAL FUSE Filed Dec. 15.I 1941 m. m m m Patented Sept. 28, 1943 RENEVABLE ELECTRICAL FUSE Harry W. Mervis, Pittsburgh, Pa., assignor to Capitol Renewable Fuse Company, Pittsburgh, Pa., a. corporation cf Pennsylvania Application December 13, 1941, Serial No. 422,816

(Cl. `,20G- 131) 2 Claims.

My invention consists in a new and improved renewable electrical fuse.

The object in View is the provision of a fuse of this character which is of inexpensive, yet of rigid and efficient character and from which a ruptured fusible link may be quickly removed and a new link installed quickly by an unskilled person and without requiring special tools.

In the accompanying drawing, wherein I have illustrated a practical embodiment of the principles of my invention,

Fig, 1 is a longitudinal section of the fuse assembled ready for use.

Fig. 2 is an enlarged elevation of one end portion of the fuse with the screw cap removed and the ferrule partially broken away to show the method of mounting the same on the end of the insulating tube.

Fig. 3 is an exploded view showing the tube with the ferrules mounted thereon, the fusible link, the bridge pieces, and the screw caps.

Fig. 4 is a plan View of one of the bridge pieces.

Referring to the drawing, II) indicates the cylindrical tube which is made oi' fibre or other suitable electrically insulating material, and upon the exteriorly reduced end portions of which are mounted the metal ferrules II which are preferably of conductive metal and interiorly threaded so as to be screwed onto the reduced ends of the tube I0.

I2 indicates a pair of radially disposed and diametrically opposed notches cut in the ends of the tube and also in the ends of the ferrules to receive the lugs or wings I3 of the T-shaped bridge pieces I4 which are thus mounted in the ends of the tube I as indicated in Fig. 1. These bridge pieces, which are preferably of conductive metal, thus span the interior of the tube adjacent the ends of the latter, with the ridges or outer edge surfaces of the bridges projecting somewhat beyond the outer ends of the ferrules.

I5 indicates the fusible link, preferably in the form of a flat strip of fusible metal having a somewhat greater length than the length of the tube I0 so that when the link is inserted in the tube, the extremities of the former will protrude from the latter, one extremity of the link prei'- erably being disposed at one side of the adjacent bridge piece while the other extremity of the link is disposed at the other side of the other bridge piece.

The protruding ends of the link are bent down at right angles across the bridge pieces, as indicated in Fig. l and in dotted lines in Fig. 3.

I6 indicates the screw caps formed of conductive material, such as copper or brass and having closed ends and annular skirts I'i" which are interioriy threaded so that they may be applied to the iuse by screwing the same onto 'the ferrules I I, the closed end or' the caps clamping the bent over extremities oi the link i5 between tne caps and the bridge pieces, thus providing a good conductive connection between the screw caps and the fusible link. The screw caps are provided with slots I8 for the application of a screw driver.

The wings I3 of the bridge pieces preferably t snugly in the slots I2 and the bodies of such pieces may rit rather snugly the bore of the tube so that the bridge pieces will not accidentally drop out oi piace from the tube.

In assembling the tube, the screw caps being removed, the fusible link is inserted in place and its protruding extremities bent down over the bridge pieces, the screw caps are then screwed nome on the ferrules and the fuse is ready for mounting in operative position. 'When a fuse has blown, the sci'ew caps are removed and the ends of the ruptured ruse are withdrawn from the tube, and tuen the operation of installing a new link, above described, is repeated.

It is evident from the foregoing that my improved 'use is of simple and inexpensive construction, and the removal of a ruptured link and the substitution of a new link an easy and quickly accomplished task,

I claim:

l. A renewable cartridge type fuse which consists of a tube of insulating material having threaded end sections oi reduced exterior diameter, internally and externally threaded metallic errules mounted on the threaded end sections or the insulating tube, the exterior or said ferrules being substantially the saine diameter as the insulating tube and having an untiireaded outer eiid portion, a pair or radially disposed and dianie'tiicaily opposed notches in the uhthreaded outer end portion oi the feirules and the corresponding portion of the insulating tube, uhipianar bridge members arranged to be inserted into the ends 0f the bore of the insulating tube, the ends of the bridge hieinbers snugly fitting the bore to frictonally maintain them therein, outwardly projecting lugs on the ends of the bridge members engaging said notches to limit the insertion thereof and to retain the outer edge of the bridge members beyond the insulating tube and the ferrules, a fusible link of greater overall length than that of the insulating tube extending through the tube and having its protruding extremities bent over the bridge pieces, and interiorly threaded screw caps engaging the ferrules to clamp the extremities of the fusible link between themselves and the bridge pieces.

2. A renewable cartridge type fuse which consists of a tube of insulating material provided at its ends with threads, a iiat T-shaped bridge member inserted in the bore ateach end of the insulating tube, the stem of the T-shaped bridge members having straight sides and being sufficiently wide to span the bore of the insulating tube and frictionally engage the diametrical interior wall surfaces to hold the bridge members against movement relative to the tube, outwardly extending lugs forming the head of the T being wider than the bore and engaging the ends of the insulating tubes to limit the insertion of the bridge members into the insulating tube and to retain the ridges of the bridge members beyond the threaded ends, a fusible link of greater overall length than that of the insulating tube and the projecting bridge members extending through the tube and having its protruding extremities bent over the ridges of the bridge members, and interiorly threaded metal screw caps engaging the threads at the ends of the insulating tube to clamp the extremities of the fusible link between themselves and the bridge members for conducting current through the fusible link and for enclosing the same.

HARRY W. MERVIS. 

